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TPS65910 VRTC power mode in OFF state

Daisuke Maeda
Guru 20205 points

Please refer to: https://e2e.ti.com/support/power_management/pmu/f/43/t/435071

I understand that since the boot mode is determined during the power-on event (OFF-to-ACTIVE transition) the VRTC is in low-power mode during OFF state after NO SUPPLY-to-OFF transition even if the VRTC_REG.VRTC_OFFMASK (EEPROM bit) = 1 (full power mode), i.e. TPS65910A31. Is my understanding correct?

I am concerned that the VRTC of TPS65910A31 does not have capability for supply to the VDDS_RTC of AM335x. For the AM335x Power Supply Connections with TPS65910A31, please refer to the following User's Guide: http://www.ti.com/lit/ug/swcu093c/swcu093c.pdf

Best regards,

Daisuke

 

  • 0
    TI__Genius 10885 points
    No, with VRTC_OFFMASK =1, VRTC will transition to full power mode in the NO SUPPLY-to-OFF transition. However, VRTC will initially default to the lower power mode for the initial VRTC turn on time of ~2.2ms, and will then require ~1.5ms to transition to the full power mode.

    Many designs have directly connected VRTC to VDDS_RTC for the TPS65910A31, just be mindful of additional loads holding VRTC low in these initial ms or the pmic will fail to turn on.
  • 0 in reply to Richard Solarski
    Guru 20205 points

    Hi Richard,

    Thank you for your reply.

    I understand that VRTC should not be supplied to VDDS_RTC of AM335x even if TPS65910A31 is used because the conditions when the VDDS_RTC maximum current rating is 5mA are not defined.

    Best regards,

    Daisuke